1. Field of the Invention
The present invention is broadly concerned with infusion devices used for the administration of various fluids to patients. More particularly, the invention is concerned with such devices having a resilient and deformable split septum unit for sealingly receiving a cannula. More preferably, the device also includes a pressure-actuated flow control device downstream from the septum for reducing the risk of blood reflux into the device during use.
2. Description of the Prior Art
The use of intravenous devices for the administration of parenteral and other fluids to patients is a common practice. A variety of devices for such purposes have been proposed in the past, such as a simple length of tubing having a fitting on one end for making connection with a source of fluid (e.g., a bottle or flexible bag), while the other end is provided with a needle or catheter which may be inserted into the vein of a patient. More commonly, however, specialized infusion devices are provided which include a venous needle (or catheter) at one end and a split septum at the other end. In the use of these devices, the needle (or catheter) is inserted into the patient and the device is taped or otherwise affixed to the patient or adjacent equipment. Thereupon, a cannula connected to a liquid supply may be inserted into the free septum end of the device in order to begin fluid therapy. The septum provides a swabable injection site that can be reused, while the needle (or catheter) remains inserted into the patient. Such devices are illustrated, e.g., in U.S. Pat. Nos. 5,632,735, 5,603,706, 5,356,396,, D320,082, D323,709,, and D323,889, (hereinafter “the Wyatt patents”).
A persistent problem with prior infusion devices is referred to as blood reflux, or the tendency for small amounts of blood from the patient to be drawn into the infusion apparatus. Among other things, this leads to clotting of the blood and occlusion of the apparatus and the need for frequent device replacement. This can be traumatizing to patients, and requires continual monitoring of the apparatus by the nursing staff. Furthermore, untrained patient treatment personnel can often over-pressurize the IV system in an effort to dislodge the occlusion, which can disconnect IV tubing or, more importantly, severely injure the patient. A prime cause of undesired and inadvertent blood reflux in prior devices stems from the negative pressures generated by removal of the cannula. Split septums further exacerbate the problem. Particularly, removal of the cannula causes a frictional pullback on the septum and resultant creation of negative pressures owing to consequent distal distortion of the septum (sometimes referred to as “drumming”).
There is accordingly a need in the art for improved infusion devices equipped with split septum units and which eliminate the possibility of blood reflux upon cannula removal.